Ruka Rengoku

Ruka is a young woman with refined features, a sharp nose, long brows, and a pale complexion. Her large dark red eyes carry round white pupils much like those of the Kamado family.

Her semi-long black hair is loosely tied at the end into a ponytail. She wears a white kimono decorated with blue and aqua flowers and bound at the waist by an obi in shades of blue.

In contrast to her loud, brash husband, Ruka is portrayed as wise, gentle, and graceful. She holds firm moral convictions and impresses upon Kyojuro the value of his own life along with the duty to use his strength on behalf of the weak and the helpless.

Shinjuro later credits her influence for the fine character of both their sons, observing that the boys took after her far more than after him despite their physical resemblance to their father.

Ruka raises Senjuro and Kyojuro alongside Shinjuro. Some time after Senjuro's birth she falls ill with an incurable disease and remains bedridden until she dies. Before her death she instills in Kyojuro the principle that the strong must shield the weak, a lesson he carries to his own final breath. Her loss devastates Shinjuro, who turns to drink and abandons his post as Flame Hashira soon after.

During Kyojuro's clash with Upper Rank Three, the mortally wounded Hashira recalls his last conversation with his mother and draws on her words for one final effort against his foe. As he slips away, he sees her once more, and she tells him he carried out his task well before he passes.